Method for recycling coal liquefaction residue

Abstract

Disclosed is a method for recycling a coal liquefaction residue. The method includes S1, drying a coal liquefaction residue and pulverizing to obtain a pulverized coal liquefaction residue; S2, subjecting the pulverized coal liquefaction residue to a solvothermal extraction in an autoclave to obtain an extract liquid and a residue; S3, distilling the extract liquid and recovering an organic solvent to obtain a solid extract.

What is claimed is: 
     
       1. A method for recycling a coal liquefaction residue, comprising:
 drying a coal liquefaction residue and pulverizing the dried coal liquefaction residue to obtain a pulverized coal liquefaction residue, the coal liquefaction residue comprising a waste product generated by a direct coal liquefaction process; 
 subjecting the pulverized coal liquefaction residue to a solvothermal extraction in an autoclave to obtain an extract liquid and a residue; and 
 distilling the extract liquid and recovering an organic solvent to obtain a solid extract. 
 
     
     
       2. The method as claimed in  claim 1 , wherein a solvent for the solvothermal extraction is N-methylpyrrolidone, and the solvothermal extraction is conducted at a temperature of 300-400° C. for 0.5-1.5 h. 
     
     
       3. The method as claimed in  claim 1 , wherein the coal liquefaction residue is dried at a temperature of 80-120° C. and pulverized to a particle size of less than or equal to 0.2 mm. 
     
     
       4. The method as claimed in  claim 1 , wherein the distilling is conducted at a temperature of 80-110° C. and a vacuum degree of less than or equal to 0.05 Mpa. 
     
     
       5. The method as claimed in  claim 1 , further comprising preparing a hot-pressed coal briquette using the solid extract as a binder, wherein the preparation of the hot-pressed coal briquette comprises:
 mixing amounts of the solid extract and raw coal to obtain a first mixture; delivering the first mixture into a hot-pressing mold; 
 placing the hot-pressing mold in a high-temperature furnace; 
 heating the hot-pressing mold, and subjecting the first mixture to heat preservation and hot-pressing molding at a set pressure; and 
 cooling the hot-pressing mold to room temperature to obtain the hot-pressed coal briquette. 
 
     
     
       6. The method as claimed in  claim 5 , wherein a weight ratio value of the solid extract to the raw coal is in the range of 5-25%, and the hot-pressing molding is conducted at a temperature of 250-500° C., and the heat preservation is conducted for 10-60 min. 
     
     
       7. The method as claimed in  claim 5 , wherein the raw coal is selected from the group consisting of bituminous coal and anthracite. 
     
     
       8. The method as claimed in  claim 1 , further comprising preparing a ceramsite using the residue obtained after subjecting the pulverized coal liquefaction residue to the solvothermal extraction in the autoclave as a raw material, wherein the preparation of the ceramsite comprises:
 mixing alumina, bentonite and the residue obtained after subjecting the pulverized coal liquefaction residue to the solvothermal extraction in the autoclave to obtain a second mixture; and 
 subjecting the second mixture to granulation, pre-heating, and high-temperature sintering to obtain a finished ceramsite product. 
 
     
     
       9. The method as claimed in  claim 8 , wherein the pre-heating is conducted at a temperature of 400-600° C. for 10-30 min, and the high-temperature sintering is conducted at a temperature of 900-1,200° C. for 10-60 min.